But they are not thresholds: A critical analysis of the documentation of threshold limit values.
Am J Ind Med 1990; 17(6):727-753
A detailed study was undertaken of the references in the 1976 Documentation to data on industrial experience and experimental human studies. The references, sorted for those including both the incidence of adverse effects and the corresponding exposure yielded 158 paired sets of data. Where the exposure was at or below the threshold limit values (TLV), only a minority of studies showed no adverse effects. The remainder indicated that up to 100% of those exposed had been affected. On repeating the search of references to human experience as listed in the more recent 1986 edition of Documentation, a very similar picture emerged from the 72 sets of clear data that were found. Three striking results emerged from this study. The TLVs were poorly correlated with the incidence of adverse effects in humans. The TLVs were well correlated with the exposure levels which had been reported at the time the limits were adopted. The interpretations of exposure response relationships were inconsistent between the authors of studies cited in the 1976 Documentation and the TLV Committee. Taken together these observations suggest that the TLVs could not have been based purely on considerations of health.
NIOSH-Publication; NIOSH-Grant; Training; Epidemiology; Toxic-effects; Threshold-limit-values; Exposure-limits; Occupational-exposure
Biomedical & Environ Hlth Scis University of California 322 Warren Hall Berkeley, Calif 94720
American Journal of Industrial Medicine
University of California Berkeley, Berkeley, California